Date:   Tue, 14 Dec 2021 14:50:48 +0100
From:   Johannes Weiner <hannes@cmpxchg.org>
To:     Muchun Song <songmuchun@bytedance.com>
Cc:     willy@infradead.org, akpm@linux-foundation.org, mhocko@kernel.org,
        vdavydov.dev@gmail.com, shakeelb@google.com, guro@fb.com,
        shy828301@gmail.com, alexs@kernel.org, richard.weiyang@gmail.com,
        david@fromorbit.com, trond.myklebust@hammerspace.com,
        anna.schumaker@netapp.com, jaegeuk@kernel.org, chao@kernel.org,
        kari.argillander@gmail.com, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-nfs@vger.kernel.org, zhengqi.arch@bytedance.com,
        duanxiongchun@bytedance.com, fam.zheng@bytedance.com,
        smuchun@gmail.com
Subject: Re: [PATCH v4 02/17] mm: introduce kmem_cache_alloc_lru
Message-ID: <YbihOFJHqvQ9hsjO@cmpxchg.org>
References: <20211213165342.74704-1-songmuchun@bytedance.com>
 <20211213165342.74704-3-songmuchun@bytedance.com>
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On Tue, Dec 14, 2021 at 12:53:27AM +0800, Muchun Song wrote:
> +/*
> + * The allocated list lru pointers array is not accounted directly.
> + * Moreover, it should not come from DMA buffer and is not readily
> + * reclaimable. So those GFP bits should be masked off.
> + */
> +#define LRUS_CLEAR_MASK	(__GFP_DMA | __GFP_RECLAIMABLE | __GFP_ACCOUNT | __GFP_ZERO)

There is already GFP_RECLAIM_MASK for this purpose, you can use that.

> +int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru,
> +			 gfp_t gfp)
> +{
> +	int i;
> +	unsigned long flags;
> +	struct list_lru_memcg *mlrus;
> +	struct list_lru_memcg_table {
> +		struct list_lru_per_memcg *mlru;
> +		struct mem_cgroup *memcg;
> +	} *table;
> +
> +	if (!list_lru_memcg_aware(lru) || memcg_list_lru_allocated(memcg, lru))
> +		return 0;
> +
> +	gfp &= ~LRUS_CLEAR_MASK;

	gfp &= GFP_RECLAIM_MASK;